From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Summary of running tests performed on twin belts (Mould No.293) with corrected pulley angles.
| Identifier | ExFiles\Box 135\1\ scan0052 | |
| Date | 6th November 1936 guessed | |
| SUMMARY OF RUNNING DONE WITH TWIN BELTS (MOULD NO.293) WITH CORRECTED PULLEY ANGLES. BELT (A) This is a standard Phantom III. belt and has been run for five hours at 4000 driving pulley r.p.m, driving the experimental fan with the standard ratio of fan speed/engine speed - i.e. .9/1 - has stretched and is slipping badly. BELT (B) This is one of the pair of twin belts to Mould No.293 - it has run one hour at 4000 driving pulley R.P.M, using the high speed ratio - i.e. 1.15/1 but with no fan fitted to driven hub. This belt ran satisfactorily with no stretch or over-heating. PAIR OF BELTS (C) These are a pair of Mould No.293 belts which have run 1½ hours at 4000 driving pulley R.P.M. with the high speed ratio,(1.15/1) and driving the experimental fan. These belts stretched very badly - became fairly hot and slipped badly. PAIR OF BELTS (D) These are a pair of Mould No.293 belts which have run as follows:- (a) Half an hour at 4000 driving pulley R.P.M., high speed ratio with no fan fitted to hub - belts O.K. (b) One hour at 4000 driving pulley R.P.M. high speed ratio and standard fan fitted - belts O.K. (c) Half an hour at 4000 driving pulley R.P.M., high speed ratio and experimental fan fitted - belts stretched badly. (d) Belts retensioned after (c) and run for one hour at 3000 driving pulley R.P.M., high speed ratio and experimental fan fitted - belts O.K. --------- | ||